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As efforts to study the mechanisms of melanoma metastasis and novel therapeutic approaches multiply, researchers need accurate, high-throughput methods to evaluate the effects on tumor burden resulting from specific interventions. We show that automated quantification of tumor content from whole slide images is a compelling solution to assess in vivo experiments. In order to increase the outflow of data collection from preclinical studies, we assembled a large dataset with annotations and trained a deep neural network for the quantitative analysis of melanoma tumor content on histopathological sections of murine models. After assessing its performance in segmenting these images, the tool obtained consistent results with an orthogonal method (bioluminescence) of measuring metastasis in an experimental setting. This AI-based algorithm, made freely available to academic laboratories through a web-interface called MetFinder, promises to become an asset for melanoma researchers and pathologists interested in accurate, quantitative assessment of metastasis burden., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Melanoma represents a critical clinical challenge owing to its unfavorable outcomes. This type of skin cancer exhibits unique adaptability to the brain microenvironment, but its underlying molecular mechanisms are poorly understood. Recent findings have suggested that melanoma brain metastases may share biological processes similar to those found in various neurodegenerative diseases. To further characterize melanoma brain metastasis development, we explore the relationship between the transcriptional profiles of melanoma brain metastases and the neurodegenerative diseases Alzheimer's disease, Parkinson's disease, and multiple sclerosis. We take an in silico approach to unveil a neurodegenerative signature of melanoma brain metastases compared with those of melanoma nonbrain metastasis (53 dysregulated genes were enriched in 11 functional terms, such as associated terms to the extracellular matrix and development) and with those of nontumor-bearing brain controls (195 dysregulated genes, mostly involved in development and cell differentiation, chromatin remodeling and nucleosome organization, and translation). Two genes, ITGA10 and DNAJC6, emerged as key potential markers being dysregulated in both scenarios. Finally, we developed an open-source, user-friendly web tool (https://bioinfo.cipf.es/metafun-mbm/) that allows interactive exploration of the complete results., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Metastatic melanoma develops once transformed melanocytic cells begin to de-differentiate into migratory and invasive melanoma cells with neural crest cell (NCC)-like and epithelial-to-mesenchymal transition (EMT)-like features. However, it is still unclear how transformed melanocytes assume a metastatic melanoma cell state. Here, we define DNA methylation changes that accompany metastatic progression in melanoma patients and discover Nuclear Receptor Subfamily 2 Group F, Member 2 - isoform 2 (NR2F2-Iso2) as an epigenetically regulated metastasis driver. NR2F2-Iso2 is transcribed from an alternative transcriptional start site (TSS) and it is truncated at the N-terminal end which encodes the NR2F2 DNA-binding domain. We find that NR2F2-Iso2 expression is turned off by DNA methylation when NCCs differentiate into melanocytes. Conversely, this process is reversed during metastatic melanoma progression, when NR2F2-Iso2 becomes increasingly hypomethylated and re-expressed. Our functional and molecular studies suggest that NR2F2-Iso2 drives metastatic melanoma progression by modulating the activity of full-length NR2F2 (Isoform 1) over EMT- and NCC-associated target genes. Our findings indicate that DNA methylation changes play a crucial role during metastatic melanoma progression, and their control of NR2F2 activity allows transformed melanocytes to acquire NCC-like and EMT-like features. This epigenetically regulated transcriptional plasticity facilitates cell state transitions and metastatic spread., (© 2023. The Author(s).)

Brain metastases are the most common brain malignancy. This review discusses the studies presented at the third annual meeting of the Melanoma Research Foundation in the context of other recent reports on the biology and treatment of melanoma brain metastases (MBM). Although symptomatic MBM patients were historically excluded from immunotherapy trials, efforts from clinicians and patient advocates have resulted in more inclusive and even dedicated clinical trials for MBM patients. The results of checkpoint inhibitor trials were discussed in conversation with current standards of care for MBM patients, including steroids, radiotherapy, and targeted therapy. Advances in the basic scientific understanding of MBM, including the role of astrocytes and metabolic adaptations to the brain microenvironment, are exposing new vulnerabilities which could be exploited for therapeutic purposes. Technical advances including single-cell omics and multiplex imaging are expanding our understanding of the MBM ecosystem and its response to therapy. This unprecedented level of spatial and temporal resolution is expected to dramatically advance the field in the coming years and render novel treatment approaches that might improve MBM patient outcomes., (© 2022 The Authors. Pigment Cell & Melanoma Research published by John Wiley & Sons Ltd.)

Melanoma brain metastasis (MBM) frequently occurs in patients with advanced melanoma; yet, our understanding of the underlying salient biology is rudimentary. Here, we performed single-cell/nucleus RNA-seq in 22 treatment-naive MBMs and 10 extracranial melanoma metastases (ECMs) and matched spatial single-cell transcriptomics and T cell receptor (TCR)-seq. Cancer cells from MBM were more chromosomally unstable, adopted a neuronal-like cell state, and enriched for spatially variably expressed metabolic pathways. Key observations were validated in independent patient cohorts, patient-derived MBM/ECM xenograft models, RNA/ATAC-seq, proteomics, and multiplexed imaging. Integrated spatial analyses revealed distinct geography of putative cancer immune evasion and evidence for more abundant intra-tumoral B to plasma cell differentiation in lymphoid aggregates in MBM. MBM harbored larger fractions of monocyte-derived macrophages and dysfunctional TOX + CD8 + T cells with distinct expression of immune checkpoints. This work provides comprehensive insights into MBM biology and serves as a foundational resource for further discovery and therapeutic exploration., Competing Interests: Declaration of interests B.I. has received honoraria from consulting with Merck, Janssen Pharmaceuticals, Astra Zeneca, and Volastra Therapeutics. M.A.D. has been a consultant to Roche/Genentech, Array, Pfizer (New York, NY, United States of America), Novartis, BMS, GSK, Sanofi-Aventis (Bridgewater, NJ, United States of America), Vaccinex, Apexigen, EISAI, and ABM Therapeutics and he has been the PI of research grants to MD Anderson by Roche/Genentech (South San Francisco, CA, United States of America), GSK, Sanofi-Aventis, Merck, Myriad, and Oncothyreon. A.R. has received honoraria from consulting with CStone, Merck, and Vedanta, is or has been a member of the scientific advisory board and holds stock in Advaxis, Appia, Apricity, Arcus, Compugen, CytomX, Highlight, ImaginAb, ImmPact, ImmuneSensor, Inspirna, Isoplexis, Kite-Gilead, Lutris, MapKure, Merus, PACT, Pluto, RAPT, Synthekine, and Tango, has received research funding from Agilent (Santa Clara, CA, United States of America) and from Bristol-Myers Squibb through Stand Up to Cancer (SU2C), and patent royalties from Arsenal Bio. T.E. has acted as a consultant for Almiral Hermal, Bristol-Myers Squibb, MSD, Novartis, Pierre Fabre, and Sanofi. E.Z.M. is a consultant for Curio Bioscience. The other authors do not declare competing interests., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Brain metastasis is a significant cause of morbidity and mortality in multiple cancer types and represents an unmet clinical need. The mechanisms that mediate metastatic cancer growth in the brain parenchyma are largely unknown. Melanoma, which has the highest rate of brain metastasis among common cancer types, is an ideal model to study how cancer cells adapt to the brain parenchyma. Our unbiased proteomics analysis of melanoma short-term cultures revealed that proteins implicated in neurodegenerative pathologies are differentially expressed in melanoma cells explanted from brain metastases compared with those derived from extracranial metastases. We showed that melanoma cells require amyloid beta (Aβ) for growth and survival in the brain parenchyma. Melanoma-secreted Aβ activates surrounding astrocytes to a prometastatic, anti-inflammatory phenotype and prevents phagocytosis of melanoma by microglia. Finally, we demonstrate that pharmacologic inhibition of Aβ decreases brain metastatic burden., Significance: Our results reveal a novel mechanistic connection between brain metastasis and Alzheimer's disease, two previously unrelated pathologies; establish Aβ as a promising therapeutic target for brain metastasis; and demonstrate suppression of neuroinflammation as a critical feature of metastatic adaptation to the brain parenchyma. This article is highlighted in the In This Issue feature, p. 1171., (©2022 American Association for Cancer Research.)

Metastasis is a complex process, requiring cells to overcome barriers that are only incompletely modeled by in vitro assays. A systematic workflow was established using robust, reproducible in vivo models and standardized methods to identify novel players in melanoma metastasis. This approach allows for data inference at specific experimental stages to precisely characterize a gene's role in metastasis. Models are established by introducing genetically modified melanoma cells via intracardiac, intradermal, or subcutaneous injections into mice, followed by monitoring with serial in vivo imaging. Once preestablished endpoints are reached, primary tumors and/or metastases-bearing organs are harvested and processed for various analyses. Tumor cells can be sorted and subjected to any of several 'omics' platforms, including single-cell RNA sequencing. Organs undergo imaging and immunohistopathological analyses to quantify the overall burden of metastases and map their specific anatomic location. This optimized pipeline, including standardized protocols for engraftment, monitoring, tissue harvesting, processing, and analysis, can be adopted for patient-derived, short-term cultures and established human and murine cell lines of various solid cancer types.

The contribution of epigenetic dysregulation to metastasis remains understudied. Through a meta-analysis of gene expression datasets followed by a mini-screen, we identified Plant Homeodomain Finger protein 8 (PHF8), a histone demethylase of the Jumonji C protein family, as a previously unidentified prometastatic gene in melanoma. Loss- and gain-of-function approaches demonstrate that PHF8 promotes cell invasion without affecting proliferation in vitro and increases dissemination but not subcutaneous tumor growth in vivo, thus supporting its specific contribution to the acquisition of metastatic potential. PHF8 requires its histone demethylase activity to enhance melanoma cell invasion. Transcriptomic and epigenomic analyses revealed that PHF8 orchestrates a molecular program that directly controls the TGFβ signaling pathway and, as a consequence, melanoma invasion and metastasis. Our findings bring a mechanistic understanding of epigenetic regulation of metastatic fitness in cancer, which may pave the way for improved therapeutic interventions.

High spliceosome activity is a dependency for cancer cells, making them more vulnerable to perturbation of the splicing machinery compared to normal cells. To identify splicing factors important for prostate cancer (PCa) fitness, we performed pooled shRNA screens in vitro and in vivo. Our screens identified heterogeneous nuclear ribonucleoprotein M (HNRNPM) as a regulator of PCa cell growth. RNA- and eCLIP-sequencing identified HNRNPM binding to transcripts of key homeostatic genes. HNRNPM binding to its targets prevents aberrant exon inclusion and backsplicing events. In both linear and circular mis-spliced transcripts, HNRNPM preferentially binds to GU-rich elements in long flanking proximal introns. Mimicry of HNRNPM-dependent linear-splicing events using splice-switching-antisense-oligonucleotides was sufficient to inhibit PCa cell growth. This suggests that PCa dependence on HNRNPM is likely a result of mis-splicing of key homeostatic coding and non-coding genes. Our results have further been confirmed in other solid tumors. Taken together, our data reveal a role for HNRNPM in supporting cancer cell fitness. Inhibition of HNRNPM activity is therefore a potential therapeutic strategy in suppressing growth of PCa and other solid tumors., Competing Interests: JH, FD, MS, DL, DI, FG, TT, JZ, HW, LC, OA, TC, AH, SZ, VR, SC, AK, MA, HH, BG, SO, MS, GG, KM, EH, DM, IM, DW, EG No competing interests declared, (© 2021, Ho et al.)

Metastasis is the primary cause of death of cancer patients. Dissecting mechanisms governing metastatic spread may uncover important tumor biology and/or yield promising therapeutic insights. Here, we investigated the role of circular RNAs (circRNA) in metastasis, using melanoma as a model aggressive tumor. We identified silencing of cerebellar degeneration-related 1 antisense (CDR1as), a regulator of miR-7, as a hallmark of melanoma progression. CDR1as depletion results from epigenetic silencing of LINC00632, its originating long non-coding RNA (lncRNA) and promotes invasion in vitro and metastasis in vivo through a miR-7-independent, IGF2BP3-mediated mechanism. Moreover, CDR1as levels reflect cellular states associated with distinct therapeutic responses. Our study reveals functional, prognostic, and predictive roles for CDR1as and expose circRNAs as key players in metastasis., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: The triple disaster that struck the Tohoku region on March 11, 2011, has had massive psychiatric, social, and physical effects on the people of Japan. A staggering loss of life and property, as well as an ongoing nuclear disaster, has dramatically affected the ability of the country to recover., Objective: In an effort to better understand the current social, health, and mental health needs of the region affected by the disaster and to share lessons from 9/11, a group of 9/11 survivors and doctors from the Icahn School of Medicine at Mount Sinai traveled to sites throughout the Fukushima, Miyagi, and Iwate prefectures., Methods: A qualitative analysis was performed on transcripts of the cultural and medical exchanges, which occurred on this trip to identify relevant themes about the problems confronting the recovery effort almost 3 years after the disaster., Findings: Significant themes that emerged included a crippling radiation anxiety, a considerable stigma toward addressing mental health care, and a shortage of mental health care throughout the region, as well as ongoing psychiatric symptoms such as insomnia, anxiety, and alcohol misuse., Conclusions: These issues continue to complicate the recovery effort but suggest avenues for future interventions., (Copyright © 2014 Icahn School of Medicine at Mount Sinai. Published by Elsevier Inc. All rights reserved.)